The prevailing standard that still dominates the Supreme Court’s current Fourth Amendment jurisprudence came from Justice John Marshall Harlan’s concurring opinion in Katz. Harlan wrote that the important question was whether a person had a “reasonable expectation of privacy.” He explained that this was a two-part test: “first that a person have exhibited an actual (subjective) expectation of privacy and, second, that the expectation be one that society is prepared to recognize as ‘reasonable.’”